gopkg.in/ubuntu-core/snappy.v0@v0.0.0-20210902073436-25a8614f10a6/kernel/kernel.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2020 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package kernel
    21  
    22  import (
    23  	"fmt"
    24  	"io/ioutil"
    25  	"os"
    26  	"path/filepath"
    27  	"regexp"
    28  
    29  	"gopkg.in/yaml.v2"
    30  )
    31  
    32  type Asset struct {
    33  	// TODO: we may make this an (optional) map at some point in
    34  	//       the future to select what things should be updated.
    35  	//
    36  	// Update set to true indicates that assets shall be updated.
    37  	Update  bool     `yaml:"update,omitempty"`
    38  	Content []string `yaml:"content,omitempty"`
    39  }
    40  
    41  type Info struct {
    42  	Assets map[string]*Asset `yaml:"assets,omitempty"`
    43  }
    44  
    45  // ValidAssetName is a regular expression matching valid asset name.
    46  var ValidAssetName = regexp.MustCompile("^[a-zA-Z0-9][a-zA-Z0-9-]*$")
    47  
    48  // InfoFromKernelYaml reads the provided kernel metadata.
    49  func InfoFromKernelYaml(kernelYaml []byte) (*Info, error) {
    50  	var ki Info
    51  
    52  	if err := yaml.Unmarshal(kernelYaml, &ki); err != nil {
    53  		return nil, fmt.Errorf("cannot parse kernel metadata: %v", err)
    54  	}
    55  
    56  	for name := range ki.Assets {
    57  		if !ValidAssetName.MatchString(name) {
    58  			return nil, fmt.Errorf("invalid asset name %q, please use only alphanumeric characters and dashes", name)
    59  		}
    60  	}
    61  
    62  	return &ki, nil
    63  }
    64  
    65  // ReadInfo reads the kernel specific metadata from meta/kernel.yaml
    66  // in the snap root directory if the file exists.
    67  func ReadInfo(kernelSnapRootDir string) (*Info, error) {
    68  	p := filepath.Join(kernelSnapRootDir, "meta", "kernel.yaml")
    69  	content, err := ioutil.ReadFile(p)
    70  	// meta/kernel.yaml is optional so we should not error here if
    71  	// it is missing
    72  	if os.IsNotExist(err) {
    73  		return &Info{}, nil
    74  	}
    75  	if err != nil {
    76  		return nil, fmt.Errorf("cannot read kernel info: %v", err)
    77  	}
    78  	return InfoFromKernelYaml(content)
    79  }